1. Field of the Invention
The present invention relates, in general, to door operators for opening and closing doors.
2. Information Disclosure Statement
Various door operators have been developed for opening and closing swing-type doors and the like. The typical door operator includes a motor, linkage means for coupling the drive shaft of the motor to a door so that the door will be opened and closed when the drive shaft rotates, and control means for activating the motor when it is desired to open or close the door. The control means may include various switch means such as, for example, pressure activated floor switches, ultrasonic presence sensors, motion sensors, radio transmitters, wall switches, etc. Such control means may also include speed control means for controlling the speed of the motor, limit means for controlling the amount of movement of the door, logic means for controlling the direction of the door is moved, etc. Richards Wilcox of 174 Third St., Aurora, IL has manufactured a swing door operator (Model 1501) that includes an operator unit having a motor, belt drive, and safety clutch for being mounted to the face of the door to be opened, and that includes linkage for extending from the operator unit to the wall adjacent the door.
Problems occur with prior art door operators when the door to be opened and/or closed is extremely heavy (such as explosion resistant doors or lead lined radiation resistant doors used in cancer treatment clinics, etc.), is subjected to high pressure differentials, or is subjected to high winds, etc. More specifically, due to the heavy weight of certain doors or the high pressure that must be overcome to open and/or close certain doors, prior door operators designed for use with such doors use substantial force to open and/or close such doors to overcome the heavy weight and high pressure required. However, such force affects the life of the door and associated structure (i.e., the force used places substantial stress on the doors and associated structure), and creates unsafe conditions (e.g., the force at which the doors are opened and/or closed can injure persons passing therethrough, etc.).
The prior art does not disclose or suggest the present invention. More specifically, the prior art does not disclose or suggest a door operator including linkage for being attached to a door; a motor having a drive shaft; and a drive train for coupling the drive shaft of the motor to the linkage, the drive train including a clutch for selectively disconnecting the linkage from the drive shaft of the motor and variable torque control means for varying the torque produced by the clutch means.